scholarly journals A Model Study on the Role of Wetland Zones in Lake Eutrophication and Restoration

2001 ◽  
Vol 1 ◽  
pp. 605-614 ◽  
Author(s):  
J.H. Janse ◽  
W. Ligtvoet ◽  
S. Van Tol ◽  
A.H.M. Bresser
Keyword(s):  
Nutrient Loading ◽  
Predatory Fish ◽  
Nutrient Concentrations ◽  
Fish Stock ◽  
Mixing Rate ◽  
Marsh Vegetation ◽  
Model Calculations ◽  
Critical Loading ◽  
Marsh Area

Shallow lakes respond in different ways to changes in nutrient loading (nitrogen, phosphorus). These lakes may be in two different states: turbid, dominated by phytoplankton, and clear, dominated by submerged macrophytes. Both states are self-stabilizing; a shift from turbid to clear occurs at much lower nutrient loading than a shift in the opposite direction. These critical loading levels vary among lakes and are dependent on morphological, biological, and lake management factors. This paper focuses on the role of wetland zones. Several processes are important: transport and settling of suspended solids, denitrification, nutrient uptake by marsh vegetation (increasing nutrient retention), and improvement of habitat conditions for predatory fish. A conceptual model of a lake with surrounding reed marsh was made, including these relations. The lake-part of this model consists of an existing lake model named PCLake[1]. The relative area of lake and marsh can be varied. Model calculations revealed that nutrient concentrations are lowered by the presence of a marsh area, and that the critical loading level for a shift to clear water is increased. This happens only if the mixing rate of the lake and marsh water is adequate. In general, the relative marsh area should be quite large in order to have a substantial effect. Export of nutrients can be enhanced by harvesting of reed vegetation. Optimal predatory fish stock contributes to water quality improvement, but only if combined with favourable loading and physical conditions. Within limits, the presence of a wetland zone around lakes may thus increase the ability of lakes to cope with nutrients and enhance restoration. Validation of the conclusions in real lakes is recommended, a task hampered by the fact that, in the Netherlands, many wetland zones have disappeared in the past.

Variations in nutrient concentrations at different time scales in two shallow tidally dominated estuaries

2012 ◽  
Vol 63 (2) ◽  
pp. 95 ◽  
Author(s):  
Hui W. Tay ◽  
Karin R. Bryan ◽  
Conrad A. Pilditch ◽  
Stephen Park ◽  
David P. Hamilton
Keyword(s):  
Tidal Cycle ◽  
Nutrient Loading ◽  
Inorganic Nitrogen ◽  
Monitoring Program ◽  
Field Measurements ◽  
Nutrient Concentrations ◽  
Night Time ◽  
Mass Fluxes ◽  
Frequency Monitoring

Water-quality observations in estuaries can be highly variable in time and space, making it difficult to quantify nutrient fluxes and to discriminate patterns. We measured nitrate, phosphate and ammonium concentrations in two shallow tidally dominated estuaries in Tauranga Harbour, New Zealand, during four periods (winter, start of spring, end of spring and summer) within 1 year, to determine the source of variability observed in a 19-year monitoring program. These measurements consisted of high-frequency monitoring during one 24-h period (covering a daytime flood-ebb tide and a night-time flood-ebb tide) at each estuary. Concentrations of nitrate and ammonium had distinctive tidal patterns, with rising values during ebb flows. This tidal asymmetry caused a net seaward flux of dissolved inorganic nitrogen (nitrate and ammonium), with higher exports at night. Net fluxes were 34–358 kg N per tidal cycle for nitrate and 22–93 kg N per tidal cycle for ammonium. Fluxes were large relative to previously published model-based predictions for the region, particularly during winter. Our results showed that estuarine sampling strategies need to account for tidal variability and the role of episodic runoff events, and highlighted the importance of correctly validated mass fluxes from field measurements for comparisons with nutrient-loading models.

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

Loading rates of nutrients discharging from a golf course and a neighboring forested basin

1999 ◽  
Vol 39 (12) ◽  
pp. 99-107 ◽  
Author(s):  
Takao Kunimatsu ◽  
Miki Sudo ◽  
Takeshi Kawachi
Keyword(s):  
Nutrient Loading ◽  
Chamaecyparis Obtusa ◽  
Phosphorus Loading ◽  
Golf Course ◽  
Nutrient Concentrations ◽  
Golf Courses ◽  
Japanese Cypress ◽  
Arithmetic Average ◽  
Loading Rates ◽  
Runoff Rate

In the last ten years, the number of golf courses has been increasing in some countries as the game gains popularity. This indicates, a need to estimate the nutrient loading from golf courses in order to prevent the eutrophication of water bodies. Nutrient concentrations and flow rates of a brook were measured once a week from 1989 to 1990 at two sites: Site A of a brook flowing out from D-golf course (53 ha) and Site B of the same brook discharging into the golf course from an upper forested basin (23 ha) covered mainly with planted Japanese cypress (Chamaecyparis obtusa SIEB. et ZUCC). The bedrock of the area was granite. The annual values of precipitation and mean temperature were 1947 mm and 13.5°C in 1989, respectively. The arithmetic average values of discharge from the forested basin and the golf course were 0.392 and 1.26 mg/l total nitrogen (TN), 0.0072 and 0.145 mg/l total phosphorus (TP), 0.82 and 3.53 mg/l potassium ion (K+, 5.92 and 8.24 mg/l sodium ion (Na+), 2.1 and 9.9 mg/l suspending solid (0.001–2.0 mm, SS), 0.087 and 0.147 mS/cm electric conductivity (EC), and 0.031 and 0.037 m3/km2•s specific discharge, respectively. The loading rates of the forested basin and the golf course were 5.42 and 13.5 TN, 0.133 and 3.04 TP, 8.84 and 33.9 K+, 55.0 and 73.0 Na+, and 54.3 and 118 SS in kg/ha•y. The leaching and runoff rate of nitrogen in the chemical fertilizers applied on the golf course was calculated as 32%. These results indicated the importance of controlling the phosphorus loading for the management of golf courses.

scholarly journals Role of Single-Particle Energies in Microscopic Interacting Boson Model Double Beta Decay Calculations

Universe ◽  
2021 ◽  
Vol 7 (3) ◽  
pp. 66
Author(s):  
Jenni Kotila
Keyword(s):  
Beta Decay ◽  
Single Particle ◽  
Field Potential ◽  
Double Beta Decay ◽  
Interacting Boson Model ◽  
Model Calculations ◽  
Single Particle Level ◽  
Particle Level ◽  
Boson Model

Single-particle level energies form a significant input in nuclear physics calculations where single-particle degrees of freedom are taken into account, including microscopic interacting boson model investigations. The single-particle energies may be treated as input parameters that are fitted to reach an optimal fit to the data. Alternatively, they can be calculated using a mean field potential, or they can be extracted from available experimental data, as is done in the current study. The role of single-particle level energies in the microscopic interacting boson model calculations is discussed with special emphasis on recent double beta decay calculations.

Role of ion transfer processes in acid-base regulation with temperature changes in fish

1984 ◽  
Vol 246 (4) ◽  
pp. R441-R451 ◽  
Author(s):  
N. Heisler
Keyword(s):  
Ion Transfer ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Fish Tissues ◽  
Model Calculations ◽  
Temperature Changes ◽  
Transfer Processes ◽  
Transfer Mechanisms

The contributions of transmembrane and transepithelial ion transfer processes and of nonbicarbonate buffering to the in vivo acid-base regulation have been evaluated. Model calculations were performed utilizing experimental data on transepithelial transfer of ions relevant for the acid-base regulation, the intracellular buffering properties of fish tissues, and the behavior of intracellular and extracellular pH and bicarbonate concentration with changes of temperature. The results of these studies indicate that the changes in the pK values of physiological nonbicarbonate buffers with changes in temperature support the adjustment of pH to lower values with rising temperature; however, transmembrane and transepithelial ion transfer mechanisms determine the acid-base regulation of intracellular and extracellular compartments.

The Role of Chlorine in Stratospheric Chemistry

1996 ◽  
Vol 68 (9) ◽  
pp. 1749-1756 ◽  
Author(s):  
M. J. Molina
Keyword(s):  
Laboratory Experiments ◽  
Stratospheric Ozone ◽  
The Sun ◽  
Plastic Foam ◽  
Model Calculations ◽  
Stratospheric Chemistry ◽  
Blowing Agents ◽  
Stratospheric Ozone Layer ◽  
The Earth

The chlorofluorocarbons (CFCs) are industrialchemicals used as solvents, refrigerants, plastic foam blowing agents,etc. These compounds are eventually released to the environment; theyslowly drift into the stratosphere, where they decompose, initiatinga catalytic process involving chlorine free radicals and leading toozone destruction. The stratospheric ozone layer is important for theearth's energy budget, and it shields the surface of the earth fromultraviolet radiation from the sun. Very significant depletion of theozone layer has been observed in the spring months over Antarctica duringthe last 10-15 years. Laboratory experiments, model calculations andfield measurements, which include several aircraft expeditions, haveyielded a wealth of information which clearly points to the CFCs asthe main cause of this depletion.

scholarly journals The role of predator removal by fishing on ocean carbon dynamics

2021 ◽  
Author(s):  
Rick Stafford ◽  
Zach Boakes ◽  
Alice Hall ◽  
Georgia Jones
Keyword(s):  
Predatory Fish ◽  
Fish Biomass ◽  
Predator Removal ◽  
High Productivity ◽  
Respiration Rates ◽  
Total Fish ◽  
Ocean Carbon ◽  
Global Carbon ◽  
Phytoplankton Photosynthesis

Abstract The ocean is a net sequester of carbon dioxide, predominantly through low biomass, high productivity phytoplankton photosynthesis. Selective removal of predatory fish through extractive fishing alters the community structure of the ocean, with an increased biomass of more productive, low trophic level fish and higher overall respiration rates, despite possible decreases in total fish biomass. High pressure fishing on predators may result in as much as a 19% increase in respiration from fish communities and could prove highly significant in global carbon budgets.

scholarly journals The Role of Predator Removal by Fishing on Ocean Carbon Dynamics

2021 ◽  
Author(s):  
Richard Stafford ◽  
Zach Boakes ◽  
Alice E. Hall ◽  
Georgia C. A. Jones
Keyword(s):  
Trophic Level ◽  
Carbon Dynamics ◽  
Predatory Fish ◽  
Predator Removal ◽  
Phytoplankton Communities ◽  
Total Fish ◽  
Ocean Carbon ◽  
Ocean Sequestration ◽  
Global Carbon

AbstractTotal ocean carbon exceeds 40,000 GT either dissolved in the water column or buried in ocean sediments, and the ocean continues to sequester carbon from the atmosphere. Selective removal of predatory fish through extractive fishing alters the community structure of the ocean. This altered community results in increased biomass of more productive, low trophic level fish, higher overall fish respiration rates and lower carbon sequestration rates from fish, despite possible decreases in total fish biomass. High-pressure fishing on high trophic level fish, a globally occurring phenomenon, may result in as much as a 19% increase in respiration from fish communities overall. This increase in respiration will reduce sequestration rates and could prove highly significant in global carbon budgets. Preliminary estimates suggest a loss of sequestration equating to around 90Mt C.year−1 (~ 10% of total ocean sequestration or ~ 1% of anthropogenic fossil fuel emissions per year). Ultimately, to reduce these carbon emissions, fishing needs to be carbon optimised, alongside other fisheries management outcomes, which may mean that fewer higher trophic level fish are removed. This study highlights the potential magnitude of fishing on ocean carbon dynamics and presents the key uncertainties (including understanding the effects of fishing on zoo- and phytoplankton communities) we need to urgently research to accurately quantify the effects and model future fishing practices. Graphical Abstract

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